Rotary impact tool

Abstract

Rotary impact tool, comprising the following: a case; an electric motor that is carried in the housing; A drive assembly for converting a continuous torque input from the motor into successive rotary blows onto a workpiece, the drive assembly comprising the following: an anvil with a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, wherein the bore defines a hexagonal cross-sectional shape in a plane oriented transversely to an axis of rotation of the anvil, wherein the bore has a nominal diameter of 7 / 16 inch, a hammer for transferring the successive rotary blows to the anvil, which is both rotatable and axially movable in relation to the anvil, and a spring for pre-tensioning the hammer in an axial direction towards the anvil; a battery pack carried through the housing to provide power to the motor, wherein the battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack of less than or equal to 7.5 lbs, and where the ratio of the peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. Provisional Application No. 62 / 816263, filed March 11, 2019, and to co-pending U.S. Provisional Application No. 62 / 790350, filed January 9, 2019, the entire contents of which are incorporated herein by reference. FIELD OF THE INVENTION

[0002] The present invention relates to power tools and, in particular, to rotary impact tools. BACKGROUND OF THE INVENTION

[0003] Rotary impact tools utilize a motor and drive assembly to convert continuous torque input from the motor into successive rotary impacts on a workpiece. Some rotary impact tools include an electric motor and an onboard battery to power the electric motor. SUMMARY OF THE INVENTION

[0004] The present invention, in one aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece having a fastening torque of at least 900 ft-lbs. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal bore of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 pounds. A fastening torque-to-total weight ratio is greater than or equal to 120 ft-lbs per pound.

[0005] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable with respect to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 lbs. A peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute per pound.

[0006] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable with respect to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 pounds. A ratio of the peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound.

[0007] The present invention, in another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting a continuous torque input from the motor into successive rotary impacts on a workpiece having a fastening torque of at least 975 ft-lbs. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal bore of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 8.5 pounds. A fastening torque-to-total weight ratio is greater than or equal to 114 ft-lbs per pound.

[0008] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0009] BPM is the number of beats per minute, KE Hammer,Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris the current consumed by the motor. The first power ratio (PR1) of the impact wrench is defined as: PR1=(η∝InertiaHammer)×(1216 000)

[0010] inertia Hammer is the moment of inertia of the hammer. The first power ratio of the impact wrench is greater than 1.

[0011] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0012] BPM is the number of beats per minute, KE Hammer,Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris the current consumed by the motor. A second power ratio (PR2) of the impact wrench is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000),

[0013] RPM keine Last is a rotation frequency of the impact mechanism in a state without load and inertia Hammer is the moment of inertia of the hammer. The second power ratio of the impact wrench is greater than 2.

[0014] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0015] BPM is the number of beats per minute, KE Hammer, Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris the current consumed by the motor. A third power ratio (PR3) of the impact wrench is defined as: PR3=(η∝MassHammer)×(160)

[0016] mass Hammer is the mass of the hammer. The third power ratio of the impact wrench is greater than 2.

[0017] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 7.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0018] BPM is the number of beats per minute, KE Hammer, Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris the current consumed by the motor. A fourth power ratio (PR4) of the impact wrench is defined as: PR4=(η∝×RPMno load mass hammer)×(13 600)

[0019] RPM keine Last is a rotation frequency of the impact mechanism in a state without load and mass Hammer is the mass of the hammer. The fourth power ratio of the impact wrench is greater than 65.

[0020] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 8.5 lbs. A mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0021] BPM is the number of beats per minute, KE Hammer, Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris the current drawn by the motor and the voltage across the motor. The first power ratio (PR1) of the impact wrench is defined as: PR1=(η∝InertiaHammer)×(1216 000)

[0022] inertia Hammer is the moment of inertia of the hammer. The first power ratio of the impact wrench is greater than 1.

[0023] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 8.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0024] BPM is the number of beats per minute, KE Hammer, Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris a current drawn by the motor and a voltage across the motor. A second power ratio (PR2) of the impact wrench is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000),

[0025] RPM keine Last is a rotation frequency of the impact mechanism in a state without load and inertia Hammer is the moment of inertia of the hammer. The second power ratio of the impact wrench is greater than 2.

[0026] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 8.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0027] BPM is the number of beats per minute, KE Hammer, Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor and current Motoris a current drawn by the motor and a voltage across the motor. A third power ratio (PR3) of the impact wrench is defined as: PR3=(η∝MassHammer)×(160)

[0028] Mass Hammer is the mass of the hammer. The third power ratio of the impact wrench is greater than 2.

[0029] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a battery pack supported by the housing for providing power to the motor. The battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah. The rotary impact tool, including the battery pack, has a total weight of less than or equal to 8.5 lbs. A mechanism efficiency of the rotary impact tool is defined as follows: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0030] BPM is the number of beats per minute, KE Hammer, Bohren is a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor is a voltage across the motor, and current Motoris a current drawn by the motor and a voltage across the motor. A fourth power ratio (PR4) of the impact wrench is defined as: PR4=(η∝×RPMno load mass hammer)×(13 600)

[0031] RPM keine Last is a rotation frequency of the impact mechanism in a state without load and mass Hammer is the mass of the hammer. The fourth power ratio of the impact wrench is greater than 65.

[0032] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing defining a rear side of the rotary impact tool and a top side of the rotary impact tool, an electric motor carried within the housing, a handle having a first end coupled to the housing and an opposite second end, a battery receptacle coupled to the second end of the handle, and a battery pack attachable to the battery receptacle. The battery pack defines a bottom side of the rotary impact tool and, when attached to the battery receptacle, provides power to the motor. The rotary impact tool further includes a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece.The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The distal end of the anvil defines a front face of the rotary impact tool. The drive assembly further includes a hammer for transmitting the successive rotary blows to the anvil, which hammer is both rotationally and axially movable with respect to the anvil. The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. A tool length is defined between the rear face of the rotary impact tool and the front face of the rotary impact tool.A tool height is defined between the bottom of the rotary impact tool and the top of the rotary impact tool. A ratio of the tool length to the tool height is less than or equal to 1.

[0033] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing defining a top surface of the rotary impact tool, an electric motor carried within the housing, and a handle having a first end coupled to the housing and an opposite second end. The handle has a base at the second end. The rotary impact tool further includes a battery receptacle coupled to the base of the handle and a battery pack attachable to the battery receptacle. The battery pack defines a bottom surface of the rotary impact tool and, when attached to the battery receptacle, provides power to the motor. The rotary impact tool further includes a trigger on the handle for activating the motor. The trigger has a lower lip in opposing relationship with the base of the handle.The rotary impact tool further includes a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The distal end of the anvil defines a front face of the rotary impact tool. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, which hammer is both rotationally and axially movable with respect to the anvil. The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil.A handle height is defined between an upper surface of the foot and the lower lip of the trigger, and a tool height is defined between the bottom and top of the rotary impact tool. A ratio of the handle height to the tool height is greater than or equal to 0.3.

[0034] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil and has a nominal diameter of 7 / 16 inch. The drive assembly further includes a hammer for transmitting the successive rotary impacts to the anvil, the hammer being both rotationally and axially movable relative to the anvil.The drive assembly also includes a spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a chuck having a body surrounding the anvil. The chuck is movable along the anvil between a first position in which the tool attachment is locked within the anvil and a second position in which the tool attachment is removable from the anvil. The chuck is biased toward the first position. The chuck includes knurling on an outer surface of the body and a lip extending away from the rotation axis that is graspable by a user for moving the chuck from the first position to the second position.

[0035] The present invention, in yet another aspect, provides a rotary impact tool comprising a housing, an electric motor carried in the housing, and a drive assembly for converting continuous torque input from the motor into successive rotary impacts on a workpiece. The drive assembly includes an anvil having an outer surface and a longitudinal bore in a distal end of the anvil configured to receive a tool bit for performing work on the workpiece. The tool bit has a bit recess. The bore defines a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil, and the bore has a nominal bore size of 7 / 16 inch.The drive assembly further includes a piston detent opening extending radially inward from the outer surface toward the bore, a cap detent opening extending radially inward from the outer surface toward the bore, a hammer for transmitting the successive rotary impacts to the anvil, which is both rotationally and axially movable with respect to the anvil, and a hammer spring for biasing the hammer in an axial direction toward the anvil. The rotary impact tool further includes a cap detent disposed in the cap detent opening. The cap detent is movable between a first cap detent position in which the cap detent is at least partially within the bore and a second cap detent position in which the cap detent is outside the bore. The rotary impact tool further includes a piston in the bore. The piston has a piston detent recess.The rotary impact tool further includes a piston detent disposed within the piston detent opening. The piston detent is movable between a first piston detent position, in which the piston detent is at least partially located within the piston detent recess, and a second piston detent position, in which the piston detent is located outside the piston detent recess. The rotary impact tool further includes a piston spring that biases the piston toward the distal end of the anvil, an O-ring that is at least partially disposed within the attachment detent opening, and a chuck that surrounds the anvil.The chuck is movable along the anvil between a first chuck position, in which the piston detent is prevented by the chuck from moving from the first piston detent position to the second piston detent position, and the top detent is prevented by the chuck from moving from the first top detent position to the second top detent position, and a second chuck position, in which the piston detent is movable by the piston from the first piston detent position to the second piston detent position, and the top detent is movable from the first top detent position to the second top detent position. The chuck is biased toward the first chuck position.When the chuck is in the second chuck position and the tool attachment is inserted into the bore, the O-ring is deformable by the attachment detent, allowing the attachment detent to be moved by the attachment from the first attachment detent position to the second attachment detent position. When the chuck is in the first chuck position and the tool attachment is in the bore, the attachment detent is in the attachment recess, locking the tool attachment within the bore. When the chuck is moved from the first chuck position to the second chuck position while the tool attachment is in the bore, the tool attachment can be ejected from the bore by the piston.

[0036] Other features and aspects of the invention will become apparent upon consideration of the following detailed description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. is a perspective view of an impact wrench according to an embodiment of the invention. Fig. is a top view of the impact wrench from Fig. . Fig. is a partial cross-sectional view of the impact wrench from Fig. . Fig. is a perspective view of a tool attachment for use with the impact wrench from Fig. . Fig. is a cross-sectional view of a battery pack for use with the impact wrench from Fig. . Fig. is a perspective view of an attachment locking assembly of the impact wrench of Fig. . Fig. is an enlarged perspective view of the impact wrench from Fig. , with sections removed. Fig. is a cross-sectional view of the attachment locking assembly of Fig. , wherein a chuck is in a first chuck position. Fig. is a cross-sectional view of the attachment locking assembly of Fig. , with the chuck in a second chuck position. Fig. is an enlarged perspective view of the impact wrench from Fig. with one bracket and one ring removed. Fig. is an enlarged top view of an anvil of the impact wrench from Fig. . Fig. is a perspective view of another embodiment of an attachment locking assembly for use with the impact wrench of Fig. . Fig. is a perspective view of another embodiment of an anvil for use with the impact wrench of Fig. , the features of the attachment locking assembly of Fig. includes. Fig. is a cross-sectional view of the attachment locking assembly of Fig., shown in a top locking state. Fig. is a cross-sectional view of the attachment locking assembly of Fig. , which is shown in an attachment release state.

[0037] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways. It is also to be understood that the phraseology and terminology used herein is for the purpose of description and should not be considered limiting. DETAILED DESCRIPTION

[0038] Fig.represent a power tool in the form of a rotary impact tool or impact wrench 10. The impact wrench 10 includes a motor housing 14 in which an electric motor 18 is carried ( Fig. ), an end cap 20 coupled to a rear end of the motor housing 14, a gear housing 22 at least partially housing a gear train 26, and an impact housing 30 housing an impact mechanism 32. The gear train 26 and the impact mechanism 32 are part of a drive assembly 33 for converting continuous torque input from the motor 18 into successive rotational impacts on a workpiece, as described in more detail below.

[0039] The impact mechanism 32 includes an anvil 34 on which a keyless chuck 35 of an attachment locking assembly 36 is carried, which enables locking of a tool attachment 37 ( Fig.) and facilitates its removal from the anvil 34, as described in more detail below. As also described in more detail below and in Fig. As shown, the gear train 26 transmits torque from the motor 18 to the impact mechanism 32, which transmits torque to the tool attachment 37 held within the anvil 34. As shown in Fig. As shown, the impact wrench 10 further includes a bracket 38 removably mounted to the gear housing 22 for securing a support member, such as a ring 40, to the impact wrench 10, as described in more detail below.

[0040] With reference to Fig. The impact wrench 10 also includes a handle 42 having a first end 39 coupled to the motor housing 14 and a second end 41 extending away from the motor housing 14. The second end 41 includes a base 43 with a battery receptacle 44 that receives a battery pack 46. As shown in Fig.As shown, the motor housing 14 defines the top 48 of the impact wrench 10, and when the battery pack 46 is coupled to the battery receptacle 44, the battery 46 defines the bottom 50 of the impact wrench 10 such that an overall height H1 of the impact wrench 10 (excluding the bracket 38 and the ring 40) is defined between the top 48 and the bottom 50 of the impact wrench 10. A distal end of the anvil 34 defines the front 54 of the impact wrench 10, and the end cap 38 defines the rear 56 of the impact wrench 10 such that an overall length L is defined between the front 54 and the rear 56 of the impact wrench 10.

[0041] In some embodiments, the total height H1 is 250 mm and the total length L is 203 mm, so that a ratio of the total length L to the total height H is 0.81. Because the ratio of the total length L to the total height H is less than 1, the impact wrench 10 is easier for an operator to hold and operate, since the operator's hand, when the operator grasps the handle 42, is close to a center of gravity CG ( Fig. ) of the impact wrench 10. Thus, the moment generated by the center of gravity while holding the impact wrench 10 is reduced, improving the operator's control and comfort while using the impact wrench 10.

[0042] With continued reference to Fig.The handle 42 includes a rear surface 60 and a trigger 62 that selectively electrically connects the motor 18 and the battery pack 46 to provide direct current to the motor 18 when the battery pack 46 is attached to the battery receptacle 44. The trigger 62 has a front surface 64 and a lower lip 66 in opposing relationship with the base 43. A minimum "trigger to rear grip" distance D1 is defined between the rear surface 60 of the handle 42 and the front surface 64 of the trigger 62. A grip height H2 is defined between the lower lip 66 of the trigger 62 and a top surface 72 of the base 43. In some embodiments, the handle height H2 is 87 mm, such that a ratio of the handle height H2 to the overall height H1 is 0.34. Since the ratio of the handle height H2 to the total height H1 is greater than 0.3, the impact wrench 10 is easier to handle because the handle 42 accounts for almost one-third or more than one-third of the total height H1.In some embodiments, the distance D1 from the trigger to the rear handle is 63 mm or less, which makes the impact wrench 10 more user-friendly for operators with smaller hands.

[0043] As in Fig.As shown, the battery pack 46 includes a housing 73 that encloses a plurality of battery cells 74 electrically connected to provide the desired output (e.g., nominal voltage, current capacity, etc.) of the battery pack 46. Each battery cell 74 may have a nominal voltage between about 3 volts (V) and about 5 V. The battery pack 46 is rechargeable, and the cells may have a lithium-based chemistry (e.g., lithium, lithium-ion, etc.) or any other suitable chemistry. The battery pack 46 has a nominal output voltage of at least 18 V and a nominal capacity of at least 5 ampere-hours (Ah) (e.g., with two strings of five battery cells connected in series (an "SS2P" pack)). In other embodiments, the impact wrench 10 may utilize a battery pack having a nominal capacity of at least 9 Ah (e.g., with three strings of five battery cells connected in series (a "5S3P" pack).

[0044] The motor 18, which is carried within the motor housing 14, receives power from the battery pack 46 when the battery pack 46 is coupled to the battery receptacle 44 ( Fig. ). The motor 18 is preferably a brushless direct current (“BLDC”) motor having a stator 76 having a plurality of stator windings 78 ( Fig. ). The motor 18 also includes a rotor 80 having a plurality of permanent magnets (not shown). The stator 76 has a nominal diameter of at least 60 mm, and the stator 76 has a stack length of at least 18 mm. For example, in one embodiment, the motor 18 is a BL60-18 motor having a nominal diameter of 60 mm and a stack length of 18 mm. The motor 18 has an approximate peak power of 950 watts when powered by the 5 Ah battery pack 46 (the 5S2P pack).

[0045] The rotor 80 is rotatable about an axis 84 and includes a motor output shaft 85 for driving the gear train 26, and the impact mechanism 32 is coupled to an output of the gear train 26. The gear train 26 can be configured in any of a number of different ways to provide a speed reduction between the output shaft 85 and a drive of the impact mechanism 32. With reference to Fig.The illustrated gear train 26 includes a spiral pinion 86 formed on the engine output shaft 85, a plurality of spiral planetary gears 88 meshing with the spiral pinion 86, and a spiral ring gear 90 meshing with the planetary gears 88 and non-rotatably mounted within the gear case 22. The planetary gears 88 are mounted on a camshaft 92 of the striking mechanism 32, such that the camshaft 92 acts as a planetary carrier. Accordingly, rotation of the output shaft 85 rotates the planetary gears 88, which then rotate along the inner circumference of the ring gear 90, thereby rotating the camshaft 92. The output shaft 85 is rotatably supported by a first or front bearing 96 and a second or rear bearing 100 supported by the end cap 20.

[0046] The impact mechanism 32 of the impact wrench 10 will now be described with reference to Fig.described. The impact mechanism 32 includes the anvil 34 extending from the impact housing 30. As noted above, the tool attachment 37 may be coupled to the anvil 34 for performing work on a workpiece (e.g., a fastener). The impact mechanism 32 is configured to convert the continuous rotational force or torque provided by the motor 18 and gear train 26 into an impact rotational force or intermittent application of torque to the anvil 34 when the reactive torque on the anvil 34 (e.g., due to engagement between the tool element and a fastener being worked on) exceeds a certain threshold.In the illustrated embodiment of the impact wrench 10, the impact mechanism 32 includes the camshaft 92, a hammer 104 carried on the camshaft 92 and axially displaceable relative thereto, and the anvil 34.

[0047] The impact mechanism 32 further includes a hammer spring 108 which biases the hammer 104 toward the front of the impact wrench 10 (ie, to the right in Fig. ). In other words, the hammer spring 108 biases the hammer 104 in an axial direction along the axis 84 toward the anvil 34. A thrust bearing 112 and a thrust washer 116 are positioned between the hammer spring 108 and the hammer 104. The thrust bearing 112 and the thrust washer 116 allow the hammer spring 108 and the camshaft 92 to continue rotating relative to the hammer 104 after each impact when projections 118 ( Fig.) on the hammer 104 engage in corresponding anvil projections 120 and rotation of the hammer 104 is temporarily stopped.

[0048] The camshaft 92 further includes cam grooves 124 in which corresponding cam balls 128 are received ( Fig. ). The cam balls 128 are in driving engagement with the hammer 104 such that movement of the cam balls 128 within the cam grooves 124 enables relative axial movement of the hammer 104 along the camshaft 92; when the hammer projections 118 and the anvil projections 120 are engaged, rotation of the anvil 34 stops, and the camshaft 92 continues to rotate.

[0049] In other embodiments (not shown), the impact mechanism includes a cylinder coupled to the electric motor 18 to receive torque therefrom, causing the cylinder to rotate. The cylinder at least partially defines a chamber containing an incompressible fluid (e.g., hydraulic fluid, oil, etc.). The hydraulic fluid in the chamber reduces wear and noise of the impact assembly generated by the impact of the hammer and anvil. The hammer and anvil are both at least partially positioned within the chamber. The hammer includes an opening to allow the hydraulic fluid in the chamber to flow through the hammer. A hammer spring biases the hammer toward the anvil. One such impact mechanism is described in U.S. Provisional Patent Application No. 62 / 699,911, filed on June 18, 2011.July 2018, the entire contents of which are incorporated herein by reference.

[0050] Now, the attachment locking assembly 36 of the impact wrench 10 is described with reference to Fig. In particular, the distal end of the anvil 34 includes a longitudinal bore 132 in which the tool attachment 37 can be received. As in Fig.As shown, the bore 132 has a hexagonal cross-sectional shape in a plane oriented transversely to the axis 84 and has a nominal diameter 134 of 7 / 16 inch to receive the tool attachment 37, which has a corresponding nominal diameter of 7 / 16 inch. The anvil 34 also includes a single radial slot 136 extending from the longitudinal bore 132 through the anvil 34. The attachment locking assembly 36 includes a ball detent 140 received in the radial slot 136, the chuck 35 slidably mounted on the anvil 34, a chuck spring 144 biasing the chuck 35 in a rearward direction to a first chuck position ( Fig.), and a washer 148 and a retaining ring 150 that hold the chuck spring 144 on the anvil 34. The chuck 35 includes a body portion 152 that includes a knurl 156 on an outer surface thereof. The chuck 35 also includes an annular lip 158 located at a distal end of the chuck 35 farthest from the impact housing 30. The lip 158 extends away from the body portion 152 and the axle 84 to form a flared portion of the chuck 35.

[0051] The chuck 35 also includes an inner ring 160 having an inner diameter sized to retain at least a portion of the ball detent 140 within the longitudinal bore 132, which in turn is retained within a circumferential groove 164 of the tool attachment 37 ( Fig.) to secure the tool attachment 37 within the anvil 34. The attachment locking assembly 14 also includes a detent spring 168 positioned around the anvil 34. A U-shaped finger 172 of the detent spring 168 is received within the slot 136 to bias the ball detent 140 toward the front of the slot 136 and toward the open end of the longitudinal bore 18. The chuck 35 is movable along the anvil 34 between the first chuck position ( Fig. ) and a second chuck position ( Fig. ), in which the chuck 35 is pulled forward along the anvil 34 against the preload of the chuck spring 144 until the inner ring 160 moves in front of the ball detent 140 so that a recess 176 behind the inner ring 160 is axially aligned with the ball detent 140.

[0052] In operation, to secure the tool attachment 37 within the anvil 34 while the chuck 35 is in the first chuck position, an operator need only insert the end of the tool attachment 37 with the circumferential groove 164 into the longitudinal bore 132 and press the tool attachment 37 toward the ball detent 140. Deeper insertion of the tool attachment 37 causes the tool attachment 37 to engage the ball detent 140 and push the ball detent 140 rearward against the bias of the detent spring 168. After the ball detent 140 has been pushed far enough to release the inner ring 160 on the chuck 35, the ball detent 140 is forced radially outward by the tool attachment 37 into the slot 136 and into the recess 176.The tool attachment 37 can then slide under the ball detent 140 until the ball detent 140 is received within the circumferential groove 164 in the tool attachment 37, at which time the detent spring 168 at least partially rebounds to press the ball detent 140 under the inner ring 160. Since the chuck 35 does not need to be moved to the second chuck position to secure the tool attachment 37 within the anvil 34, the operator of the impact wrench 10 only needs to use one hand to insert and secure the tool attachment 37 into the anvil 34.

[0053] To release the tool attachment 37, the operator may grasp the knurling 156 on the body portion 152 and / or the lip 158 of the chuck 35 to move the chuck 35 from the first chuck position to the second chuck position such that the recess 176 is axially aligned with the ball detent 140. The tool attachment 37 may then be withdrawn from the anvil 34, during which time the tool attachment 37 forces the ball detent 140 radially outward into the recess 176. Once the tool attachment 37 has moved past the ball detent 140, the detent spring 168 at least partially rebounds to force the ball detent 140 under the inner ring 160. The operator can then release the chuck 35, allowing the chuck spring 144 to move the chuck 35 back to the first chuck position.The knurling 156 improves the operator's grip on the chuck 35 by allowing more friction to be developed between the chuck 35 and the operator's fingers when grasping the chuck 35. Similarly, the lip 158 makes it easier for the operator to grasp the chuck 35 to move it from the first chuck position to the second chuck position because the lip 158 provides a flared portion against which the operator can exert force in a direction parallel to the axis 84.

[0054] As noted above, the bracket 38 is removably mounted on the gear housing 22 to secure the ring 40 to the impact wrench 10. With reference to Fig.The gear housing 22 includes an upwardly extending mounting portion 184 disposed between the motor housing 14 and the impact housing 30. The mounting portion 184 includes a pair of mounting holes 188 extending through a mounting surface 192. The mounting portion 184 projects radially through the motor housing 14 such that the holes 188 are exposed to the outside of the impact wrench 10. As shown in Fig. As shown, the bracket 38 can be removably coupled to the mounting portion 184 via a pair of bracket fasteners 196. Before attaching the bracket 38 to the mounting portion 184, the ring 40 can be disposed between the bracket 38 and the mounting surface 192. The ring 40 is configured to receive a cord 200 ( Fig.) attached to a user's belt, for example, to tether the impact wrench 10 to the user. Thus, the cord 200, the ring 40, and the bracket 38 cooperate to prevent the impact wrench 10 from hitting the ground if dropped by the operator. The ring 40 is configured to rotate within the bracket 38, providing flexibility in how the cord 200 tethers the impact wrench 10 to the operator.

[0055] As in Fig.As shown, four housing fasteners 204 extend through each of the impact housing 30, the gear housing 22, and the motor housing 14, in the following order, beginning with the impact housing 30 and ending within the motor housing 14. In this manner, the motor housing 14 is coupled to the impact housing 30, and the gear housing 22 is secured (i.e., sandwiched) between the motor housing 14 and the impact housing 30. Because the bracket 38 is secured to the mounting portion 184 only with the bracket fasteners 196, it is not necessary to remove the housing fasteners 204 connecting the motor housing 14 and the gear housing 22 to the impact housing 30 in order to remove the bracket 38 from the mounting portion 184. This arrangement thus provides greater convenience to the operator when removing the bracket 38 to operate or remove the ring 40.Because the bracket 38 is not secured to the impact wrench 10 by means of the housing fasteners 204, the bracket 38 can also be more easily used with various tools that have an arrangement of mounting holes similar to the arrangement of the mounting holes 188 of the mounting section 184.

[0056] When operating the impact wrench 10, the operator first inserts the tool attachment 37 into the anvil 36, as described above. The operator then depresses the trigger switch 62 to activate the motor 18, which continuously drives the gear train 26 and the camshaft 92 via the output shaft 85. As the camshaft 92 rotates, the cam balls 128 drive the hammer 104 to rotate with the camshaft 92, and the hammer projections 118 each engage drive surfaces of the anvil projections 120 to provide a blow and rotationally drive the anvil 34 and the tool attachment 37. After each blow, the hammer 104 moves or translates rearward along the camshaft 92, away from the anvil 34, causing the hammer projections 118 to disengage from the anvil projections 120. The hammer spring 108 stores a portion of the rearward energy of the hammer 104 to provide a return mechanism for the hammer 104.After the hammer projections 118 disengage from the respective anvil projections 120, the hammer 104 continues to rotate and move or translate forward toward the anvil 34, while the hammer spring 108 releases its stored energy until the drive surfaces of the hammer projections 118 re-engage the drive surfaces of the anvil projections 120 to impart another impact. As defined herein, "impact frequency" means the number of impacts transmitted per unit of time by the hammer 104 to the anvil 34, measured in "impacts per minute." Once completed with the impact driving operation, the operator may remove the tool attachment 37 from the anvil 34 as described above.

[0057] During operation of the impact wrench 10 in a no-load condition, when the anvil 34 is not being used to apply torque to a fastener, the combined rotation of the camshaft 92, the hammer 104, and the anvil 34 defines an "output speed" of the impact wrench 10, measured in revolutions per minute.

[0058] The impact wrench 10 weighs 5.9 pounds, the 5 Ah battery pack 46 (the 5S2P pack) weighs 1.55 pounds, and the 9 Ah battery pack (5S3P) weighs 2.4 pounds. Therefore, when the 5 Ah battery pack 46 is coupled to the impact wrench 10, the impact wrench 10 has a total weight of 7.45 pounds, and when the 9 Ah battery pack is coupled to the impact wrench 10, the impact wrench 10 has a total weight of 8.3 pounds. As defined herein, the term "fastening torque" means torque applied to a fastener in a direction that increases tension (i.e., in a tightening direction).

[0059] The first and second rows of TABLE 1 below list the gross weight, peak output speed, peak fastening torque, and peak impact frequency (measured in blows per minute) achieved by known, state-of-the-art 7 / 16-inch impact wrenches using a 5 Ah battery pack. The third and fourth rows of TABLE 1 below list the peak output speed, peak fastening torque, and peak impact frequency achieved by the impact wrench 10 using the battery pack 46 (the 5S2P pack - 5 Ah) and the 5S3P battery pack (9 Ah), respectively. Peak fastening torque is measured by tightening a 1-1 / 4" Grade 8 zinc-plated bolt. TABLE 1 below also lists peak output speed to gross weight ratios, calculated by dividing peak output speed by gross weight.TABLE 1 below also lists the peak fastening torque to total weight ratios, calculated by dividing the peak fastening torque by the total weight. TABLE 1 below also lists the peak impact frequency to total weight ratios, calculated by dividing the peak impact frequency by the total weight. TABLE 1 Total weight (pounds) Peak output speed (revolutions per minute) Peak fastening torque (ft-lbs) Peak beat rate (beats per minute) Ratio of peak output speed to total weight (revolutions per minute and pounds) Ratio of peak fastening torque to total weight (ft-lbs per pound) Ratio of peak stroke rate to total weight (strokes per minute and pound) First state-of-the-art impact wrench 7,6 1 900 973 2 400 250,0 128,0 315,8 Second state-of-the-art impact wrench 8,2 1 800 1 054 2 200 219,5 128,5 268,3 Impact wrench 10 with 5 Ah battery pack 46 7,45 2 420 920 2 858 324,8 123,5 383,6 Impact wrench 10 with 9 Ah battery pack 8,3 N / A 986 N / A N / A 118,7 N / A

[0060] As shown in TABLE 1, using the 5 Ah battery pack 46 and with a motor 18 capable of generating about 950 watts of power with a stator 76 having a nominal diameter of only 60 mm and a stack length of only 18 mm, the impact wrench 10 is capable of achieving a higher peak output speed to total weight ratio than any of the prior art impact wrenches, while having a lower total weight than any of the prior art impact wrenches.

[0061] Furthermore, as shown in TABLE 1, using the 5 Ah battery pack 46 and with a motor 18 capable of generating approximately 950 watts of power with a stator 76 having a nominal diameter of only 60 mm and a stack length of only 18 mm, the impact wrench 10 achieves almost the same peak fastening torque to total weight ratio as the prior art impact wrenches, while having a lower total weight than the prior art impact wrenches. Therefore, on a unit weight basis, the impact wrench 10 achieves fastening torque performance approximately equivalent to the heavier prior art impact wrenches.

[0062] Furthermore, as shown in TABLE 1, using the 5 Ah battery pack 46 and with a motor 18 capable of producing approximately 950 watts of power with a stator 76 having a nominal diameter of only 60 mm and a stack length of only 18 mm, the impact wrench 10 achieves a higher impact frequency to total weight ratio than the prior art impact wrenches while having a lower total weight than the prior art impact wrenches. Thus, the impact wrench 10 provides an operator with a lighter rotary impact tool for jobs while still achieving nearly the same or better fastening performance ratings than other known prior art 7 / 16-inch impact wrenches.

[0063] As used here, the term ‘mechanism efficiency’ (‘η a") represents how well an impact wrench performs work per unit of time per unit of power used. The mechanism efficiency is determined by multiplying the impact frequency, measured in blows per minute ("BPM"), by the kinetic energy of the hammer 104 during a loaded condition and before impact on the anvil 34 ("KE Hammer, Bohren “, measured in joules) and divided by the current consumption of the motor 18 (“current Motor “, measured in amperes) and the voltage across the motor 18 (“Voltage Motor “, measured in volts) as shown in the equation below: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor

[0064] When using the 5 Ah battery pack 46 and with a motor 18 capable of generating a power of approximately 950 watts with a stator 76 having a nominal diameter of only 60 mm and a stack length of only 18 mm, the impact wrench 10 is capable of achieving a variety of advantageous performance ratios as described below.

[0065] For example, a first power ratio (“PR1”) measures the efficiency of the impact mechanism 32 per unit inertia of the hammer 104. The first power ratio is determined by dividing the mechanism efficiency by the moment of inertia of the hammer 104 (“inertia Hammer “, measured in kg-m 2 ) and a scale factor of 216 000, as shown in the equation below: PR1=(η∝InertiaHammer)×(1216 000)

[0066] The scaling factor of 1 / 216,000 is used to reduce the first power ratio to a manageable number of significant figures (e.g., three, as shown in Table 2 below). However, other scaling factors may also be used.

[0067] A second performance ratio (“PR2”) measures the ability of the impact mechanism 32 to maintain the level at which it performs work during a transition from an unloaded condition to a loaded condition, per unit of inertia of the hammer 104. Specifically, the second performance ratio is determined by multiplying the mechanism efficiency by the rotational frequency, measured in revolutions per minute, of the impact mechanism 32 in an unloaded condition (“RPM keine Last “) and divided by the moment of inertia of the hammer 104 and a scale factor of 216,000,000, as shown in the equation below: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000),

[0068] The scaling factor of 1 / 216,000,000 is used to reduce the second power ratio to a manageable number of significant figures (e.g., three, as shown below in Table 2). However, other scaling factors may also be used.

[0069] A third power ratio (“PR3”) measures the efficiency of the striking mechanism 32 per unit mass of the hammer 104. The third power ratio is determined by dividing the mechanism efficiency by the mass of the hammer 104 (“Mass Hammer “, measured in kg) and a scale factor of 60, as shown in the equation below: PR3=(η∝MassHammer)×(160)

[0070] The scaling factor of 1 / 60 is used to reduce the third power ratio to a manageable number of significant figures (e.g., three, as shown below in Table 2). However, other scaling factors may also be used.

[0071] A fourth performance ratio ("PR4") measures the ability of the impact mechanism 32 to maintain the level of work it performs during a transition from an unloaded to a loaded condition, per unit mass of the hammer 104. Specifically, the fourth performance ratio is determined by multiplying the mechanism efficiency by the rotational frequency of the impact mechanism 32 in an unloaded condition, measured in revolutions per minute, and dividing by the mass of the hammer 104 and a scaling factor of 3,600, as shown in the equation below: PR4=(η∝×RPMno loadinertiahammer)×(13 600)

[0072] The scaling factor of 1 / 3 600 is used to reduce the third power ratio to a manageable number of significant figures (e.g., four, as shown below in Table 2). However, other scaling factors may also be used.

[0073] The first and second rows of TABLE 2 below list values ​​for impact frequency (measured in blows per minute), hammer kinetic energy (J), voltage (V), current (A), no-load speed (rpm), hammer inertia (kg-s2), hammer mass (kg), and the first, second, third, and fourth power ratios, respectively, achieved by the first and second prior art 7 / 16-inch impact wrenches discussed in TABLE 1 above using a 5 Ah battery pack in a drilling operation. The third row lists the same values ​​for a third prior art 7 / 16-inch impact wrench using a 5 Ah battery pack in a drilling operation. The fourth and fifth rows of TABLE 2 below list the same values ​​for the impact wrench 10 when using the battery pack 46 (the 5S2P pack - 5 Ah) and the 5S3P battery pack (9 Ah), respectively. TABLE 2 beats per minute Kinetic energy of the hammer (J) Voltage (V) Current (A) No-load speed (rpm) Inertia of the hammer (kg-s2) Mass of the hammer (kg) PR1 PR2 PR3 PR4 First state-of-the-art impact wrench 2 671 14,9 19,3 44,1 1 883 2,45×10 -4 0,416 0,89 1,67 1,88 59,01 Second state-of-the-art impact wrench 2 161 17,3 19,1 49,3 1 662 4,37× 10 -4 0,542 0,42 0,70 1,22 33,74 Third state-of-the-art impact wrench 2 599 11,8 19,4 39,3 1 632 2,04× 10 -4 0,357 0,91 1,49 1,88 51,11 Impact wrench 10 with 5 Ah battery pack 46 3 094 14,8 18,9 58,3 2 099 1,82× 10 -4 0,306 1,06 2,23 2,27 79,49 Impact wrench 10 with 9 Ah battery pack 3 212 16,0 18,4 62,2 2 099 1,82× 10 -4 0,306 1,14 2,40 2,44 85,29

[0074] As can be seen from TABLE 2, compared to the three 7 / 16-inch impact wrenches using a 5 Ah battery pack in a drilling operation, the impact wrench 10 with the 5 Ah battery pack 46 is the only 7 / 16-inch impact wrench capable of achieving a first power ratio greater than 1, a second power ratio greater than 2, a third power ratio greater than 2, and a fourth power ratio greater than 65. Likewise, when using a 9 Ah battery pack in a drilling operation, the impact wrench 10 is capable of achieving a first power ratio greater than 1, a second power ratio greater than 2, a third power ratio greater than 2, and a fourth power ratio greater than 65.

[0075] With respect to the first and third performance ratios, while the three prior art 7 / 16-inch impact wrenches benefit from larger hammers than impact wrench 10 in terms of peak fastening torque (see TABLE 1), they are at a disadvantage when evaluating the first and third performance ratios because the larger hammers also result in a higher moment of inertia. Because impact wrench 10 has a smaller and lighter hammer 104 and still achieves comparable mechanism efficiency to the three prior art 7 / 16-inch impact wrenches, it achieves a first performance ratio greater than 1 and a third performance ratio greater than 2 because the moment of inertia of hammer 104 (relevant to the first performance ratio) is lower due to the smaller and lighter hammer 104 (relevant to the third performance ratio).Thus, the efficiency of the impact mechanism 32 per unit of inertia of the hammer 104 of the impact wrench 10 (first power ratio) or per unit of mass of the hammer 104 (third power ratio) is greater than that of the three prior art 7 / 16-inch impact wrenches.

[0076] With respect to the second and fourth performance ratios, impact wrenches that have a high no-load speed (at the beginning of an operation) and a high loaded speed (evaluated by the kinetic energy of the hammer 104 in a pre-impact state) are advantageous, since during a drilling or fastening operation, it is advantageous for the impact mechanism 32 to have both a high initial speed (no load) and a high speed in the loaded state (during the operation) that is maintained until the operation is completed. Because the impact wrench 10 has a smaller hammer 104 while achieving a higher no-load speed than the three prior art 7 / 16-inch impact wrenches, it achieves a second performance ratio greater than 2 and a fourth performance ratio greater than 65.Thus, the impact mechanism 32 of the impact wrench 10 is better able to maintain the level at which it performs work during a transition from a no-load condition to a loaded condition, per unit of inertia of the hammer 104 (second power ratio) or per unit of mass of the hammer 104 (fourth power ratio), compared to the three prior art 7 / 16-inch impact wrenches shown in TABLE 2 above.

[0077] The impact wrench 10 is particularly effective in drilling operations because it simultaneously achieves a first power ratio greater than 1, a second power ratio greater than 2, a third power ratio greater than 2, and a fourth power ratio greater than 65.

[0078] An alternative embodiment of an attachment locking assembly 208 for the impact wrench 10 will now be described with reference to Fig.described. A distal end 210 of an anvil 212 includes a longitudinal bore 216 in which the tool attachment 37 can be received. Like the bore 132 of the anvil 34, the bore 216 of the anvil 212 has a hexagonal cross-sectional shape in a plane oriented transversely to the axis 84 and has a nominal diameter of 7 / 16 inch to receive the tool attachment 37. The anvil 212 has an outer surface 220 and a circumferential groove 224 ( Fig. ) to accommodate a clamp 228 ( Fig. ). Also disposed on the outer surface 220 is a bearing 232 for rotatably supporting the anvil 212 within the impact housing 30. In some embodiments, the bearing 232 is press-fitted into the anvil 212. The anvil 212 also has a circumferential O-ring groove 236 ( Fig. ) in which an O-ring 240 ( Fig. ) is held.

[0079] The anvil 212 further includes a pair of radial piston detent apertures 244 and a radial top detent aperture 248, all extending radially inward from the outer surface 220 to the bore 216 ( Fig. ). The top locking opening 248 intersects the O-ring groove 236 so that the O-ring 240 is at least partially disposed within the top locking opening 248. As shown in Fig. As shown, a pair of piston detents 252 are each disposed in the piston detents openings 244 and a top detents 256 are disposed in the top detents opening 248. As shown in Fig. As shown, a piston 260 is disposed within the bore 216 and is biased toward the distal end 210 of the anvil 212 by a piston spring 268, which is also disposed within the bore 216. The piston 260 includes a circumferential piston detent recess 270.

[0080] The attachment locking assembly 208 includes the O-ring 240, the attachment detent 256 received in the attachment detent opening 248, a chuck 272 slidably disposed on the anvil 212, a chuck spring 276 biasing the chuck 272 in a rearward direction to a first chuck position ( Fig. ), and a washer 280, which holds the chuck spring 276 on the anvil 212. As in Fig. shown, the washer 280 is arranged between the O-ring 240 and the chuck spring 276, with the washer 280 abutting the O-ring 240. As shown in Fig.As shown, the chuck 272 may include ribs 282 on an outer surface 283 thereof to improve the operator's grip on the chuck 272. The clamp 228 limits the extent to which the chuck spring 276 can push the chuck 272 rearward, so that the first position is defined by the chuck 272 abutting against the clamp 228, as shown in Fig. shown.

[0081] The chuck 272 includes a first inner piston detent surface 284 and a second inner piston detent surface 288 having a larger diameter than the first inner piston detent surface 284. The chuck 272 also includes a first inner top detent surface 292 and a second inner top detent surface 296 having a larger diameter than the first inner top detent surface 292. In the first chuck position ( Fig.), the first inner piston detent surface 284 is axially aligned with the piston detent openings 244 such that the piston detents 252 are radially inhibited by the first inner piston detent surface 284, and the first inner cap detent surface 292 is axially aligned with the cap detent opening 248. As in Fig. As shown, when the chuck 272 is in the first chuck position, the piston spring 268 is maintained in a compressed state by the piston detents 252 being prevented from moving in a radially outward direction by the first inner piston detent surface 284. Thus, the piston detents 252 are retained in the piston detent recess 270, which keeps the piston 260 axially biased against the piston spring 268.

[0082] The chuck 272 is movable along the anvil 212 between the first chuck position ( Fig. ) and a second chuck position ( Fig.), in which the chuck 272 is pulled forward along the anvil 212 against the bias of the chuck spring 276 until the first inner piston detent surface 284 is axially in front of the piston detent openings 244, the second inner piston detent surface 288 is axially aligned with the piston detent openings 244, the first inner cap detent surface 292 is axially in front of the cap detent opening 248, and the second inner cap detent surface 296 is axially aligned with the cap detent opening 248.

[0083] In operation, an operator must secure the tool attachment 37 within the anvil 212 while the chuck 272 is in the second chuck position ( Fig.), insert only the end of the tool attachment 37 with the circumferential groove 164 into the longitudinal bore 216 and press the tool attachment 37 towards the piston 260. Deeper insertion of the tool attachment 37 causes the tool attachment 37 to engage the attachment detent 256 and press the attachment detent 256 radially outward into the attachment detent opening 248 until it abuts the first inner attachment detent surface 292, whereby the O-ring 240 is elastically deformed until the attachment detent 256 is pressed out of the longitudinal bore 216. Once the attachment detent 256 is pushed out of the longitudinal bore, the tool attachment 37 can slide past the attachment detent 256 until the attachment detent 256 is axially aligned with the circumferential groove 164 in the tool attachment 37, during which time the O-ring 240 elastically springs back to press the attachment detent 256 into the circumferential groove 164. The tool attachment 37 is then locked within the bore 216.

[0084] As the tool attachment 37 moves rearward in the longitudinal bore 216, the tool attachment 37 also pushes the piston 260 rearward, which compresses the piston spring 268 so that the piston detents 252 are axially aligned with the piston detent recess 270. The chuck spring 276 can thus push the chuck 272 rearward, causing the piston detents 252 to be pushed into the piston detent recess 270. The chuck spring 276 then pushes the chuck 272 further rearward until the first inner piston detent surface 284 is axially aligned with the piston detent openings 244 and the chuck 272 is in the first chuck position. Since the operator cannot manually move the chuck 272 from the second chuck position to the first chuck position ( Fig.) to secure the tool attachment 37 within the anvil 212, the operator of the impact wrench 10 only needs to use one hand to insert and secure the tool attachment 37 into the anvil 34.

[0085] To release the tool attachment 37, the operator moves the chuck 272 from the first chuck position to the second chuck position. The ribs 282 make it easier for the operator to grip the chuck 272 when moving it from the first chuck position to the second chuck position because the ribs 282 provide flared portions against which the operator can apply force in a direction parallel to the axis 84. Movement of the chuck 272 to the second chuck position causes the second inner piston detent surface 288 to become axially aligned with the piston detent openings 244 and the second inner attachment detent surface 296 to become axially aligned with the attachment detent opening 248.

[0086] Because the piston detents 252 are no longer radially constrained by the first inner piston detent surface 288, the piston spring 268 is able to rebound, urging the piston 260 toward the distal end 210 of the anvil 212, thereby causing the piston detents 252 to move radially outward within the piston detent apertures 244 until they are outside the piston detent recess 270 and abut the second inner piston detent surface 288 of the chuck 272. Because the attachment detent 256 is no longer radially constrained by the first inner attachment detent surface 292, the tool attachment 37 is no longer locked within the bore 216, and consequently, the piston 260 ejects the tool attachment 37 from the bore 216.

[0087] When the tool attachment 37 is ejected from the bore 216 by the piston 260, the attachment detent 256 is pushed radially outward by the tool attachment 37 into the attachment detent opening 248 until it abuts the second inner attachment detent surface 296. When the attachment detent 256 is pushed radially outward by the tool attachment 37, the movement of the attachment detent 256, and thus the movement of the tool attachment 37, is impeded by the O-ring 240 as it exits the bore 216 because the attachment detent 256 must frictionally engage the O-ring 240 as it is moved toward the second inner attachment detent surface 296. Because the O-ring 240 resists the movement of the tool attachment 37 out of the bore 216, the tool attachment 37 is prevented from being suddenly ejected from the bore 216 when the chuck 272 is moved to the second chuck position.Thus, it is easier for an operator to grasp or hold the tool attachment 37 as it is ejected from the bore 216.

[0088] The operator can then release the chuck 272. When the chuck 272 is released, the chuck 272 is held in the second position by the piston spring 268, which urges the piston 260 forward, so that the piston detents 252 are held against an intermediate flat 300 of the piston 260, the diameter of which is larger than the piston detents recess 270. Thus, the piston detents 252 are held against the second inner piston detents surface 288 of the chuck 272, preventing the chuck spring 276 from returning the chuck 272 to the first chuck position. The chuck 272 is thus held in the second chuck position, ready for re-insertion of the tool attachment 37, as described above.

[0089] Various features of the invention are set forth in the following claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 62 / 816263

[0001] US 62 / 790350

[0001] US 62 / 699911

[0049]

Claims

[1] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 7.5 lbs, and wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [2] A rotary impact tool according to claim 1, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [3] The rotary impact tool of claim 1, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute and pound. [4] The rotary impact tool according to claim 1, wherein a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertia Hammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [5] A rotary impact tool according to claim 4, wherein a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition, and wherein the second power ratio of the rotary impact tool is greater than 2. [6] A rotary impact tool according to claim 5, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [7] A rotary impact tool according to claim 6, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMnoloadMassHammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [8] The rotary impact tool of claim 1, wherein the ratio of the peak output speed of the drive assembly to the total weight is greater than or equal to 320 revolutions per minute and pound. [9] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 7.5 lbs, and wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound. [10] A rotary impact tool according to claim 9, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [11] A rotary impact tool according to claim 9, wherein a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motora current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertia Hammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [12] A rotary impact tool according to claim 11, wherein a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition, and wherein the second power ratio of the rotary impact tool is greater than 2. [13] A rotary impact tool according to claim 12, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammera mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [14] A rotary impact tool according to claim 13, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4(η∝×RPMnoloadMassHammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [15] The rotary impact tool of claim 9, wherein the ratio of the peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 380 impacts per minute per pound. [16] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotary impacts with a fastening torque of at least 975 ft-lbs on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 8.5 lbs, where a fastening torque to total weight ratio is greater than or equal to 114 ft-lbs per pound. [17] A rotary impact tool according to claim 16, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [18] A rotary impact tool according to claim 16, wherein a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertia Hammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [19] A rotary impact tool according to claim 18, wherein a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition, and wherein the second power ratio of the rotary impact tool is greater than 2. [20] A rotary impact tool according to claim 19, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [21] A rotary impact tool according to claim 20, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMnoloadMassHammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [22] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 7.5 lbs, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertiaHammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [23] A rotary impact tool according to claim 22, wherein a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition, and wherein the second power ratio of the rotary impact tool is greater than 2. [24] A rotary impact tool according to claim 23, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [25] A rotary impact tool according to claim 24, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMno loadmasshammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [26] A rotary impact tool according to claim 22, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [27] The rotary impact tool of claim 22, wherein the drive assembly is configured to convert a continuous torque input from the motor into successive rotary impacts on the workpiece with a fastening torque of at least 900 ft-lbs, and wherein a ratio of the fastening torque to the total weight is greater than or equal to 120 ft-lbs per pound. [28] The rotary impact tool of claim 22, wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [29] The rotary impact tool of claim 22, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound. [30] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 7.5 lbs, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition and inertia Hammer is a moment of inertia of the hammer, and wherein the second power ratio of the rotary impact tool is greater than 2. [31] A rotary impact tool according to claim 30, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [32] A rotary impact tool according to claim 31, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMno loadmasshammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [33] A rotary impact tool according to claim 30, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [34] The rotary impact tool of claim 30, wherein the drive assembly is configured to convert a continuous torque input from the motor into successive rotary impacts on the workpiece with a fastening torque of at least 900 ft-lbs, and wherein a ratio of the fastening torque to the total weight is greater than or equal to 120 ft-lbs per pound. [35] The rotary impact tool of claim 30, wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [36] The rotary impact tool of claim 30, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute and pound. [37] The rotary impact tool of claim 30, wherein the second power ratio of the rotary impact tool is greater than 2.

2. [38] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 7.5 lbs, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [39] A rotary impact tool according to claim 38, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMnoloadMassHammer)×(13 600), where RPM keine Lasta rotation frequency of the impact mechanism in a no-load condition, and where the fourth power ratio of the rotary impact tool is greater than 65. [40] A rotary impact tool according to claim 38, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [41] The rotary impact tool of claim 38, wherein the drive assembly is configured to convert a continuous torque input from the motor into successive rotary impacts on the workpiece with a fastening torque of at least 900 ft-lbs, and wherein a ratio of the fastening torque to the total weight is greater than or equal to 120 ft-lbs per pound. [42] The rotary impact tool of claim 38, wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [43] The rotary impact tool of claim 38, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound. [44] The rotary impact tool of claim 38, wherein the third power ratio of the rotary impact tool is greater than 2.

2. [45] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing for providing power to the motor, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah; wherein the rotary impact tool has a total weight including the battery pack that is less than or equal to 7.5 lbs, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMnoloadMassHammer)×(13 600), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition and mass Hammer a mass of the hammer, and where the fourth power ratio of the rotary impact tool is greater than 65. [46] A rotary impact tool according to claim 45, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [47] The rotary impact tool of claim 45, wherein the drive assembly is configured to convert a continuous torque input from the motor into successive rotary impacts on the workpiece with a fastening torque of at least 900 ft-lbs, and wherein a ratio of the fastening torque to the total weight is greater than or equal to 120 ft-lbs per pound. [48] ​​The rotary impact tool of claim 45, wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [49] The rotary impact tool of claim 45, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound. [50] The rotary impact tool of claim 45, wherein the fourth power ratio of the rotary impact tool is greater than 70. [51] The rotary impact tool of claim 45, wherein the fourth power ratio of the rotary impact tool is greater than 75. [52] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing to provide power to the motor, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motora current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertia Hammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [53] The rotary impact tool of claim 52, wherein the first power ratio of the rotary impact tool is greater than 1.

1. [54] A rotary impact tool according to claim 52 or 53, wherein the bore has a nominal diameter of 7 / 16 inch. [55] The rotary impact tool of any of claims 52-54, wherein the battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah, and wherein the rotary impact tool has a total weight including the battery pack of less than or equal to 8.5 lbs. [56] A rotary impact tool according to any one of claims 52-55, wherein the rotary impact tool has a total weight, excluding the battery pack, of 5.9 pounds. [57] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing to provide power to the motor, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition and inertia Hammer is a moment of inertia of the hammer, and wherein the second power ratio of the rotary impact tool is greater than 2. [58] The rotary impact tool of claim 57, wherein the second power ratio of the rotary impact tool is greater than 2.

2. [59] The rotary impact tool of claim 58, wherein the second power ratio of the rotary impact tool is 2.

4. [60] The rotary impact tool of any of claims 57-59, wherein the bore defines a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah, and the rotary impact tool having a total weight including the battery pack of less than or equal to 8.5 lbs. [61] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing to provide power to the motor, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohrena kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motor a current consumed by the motor, where a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [62] The rotary impact tool of claim 61, wherein the third power ratio of the rotary impact tool is greater than 2.

2. [63] The rotary impact tool of claim 62, wherein the third power ratio of the rotary impact tool is greater than 2.

4. [64] The rotary impact tool of any of claims 61-63, wherein the bore defines a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah, and the rotary impact tool having a total weight including the battery pack of less than or equal to 8.5 lbs. [65] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving the workpiece or a tool attachment for performing work on the workpiece, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; a battery pack carried by the housing to provide power to the motor, where a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motor a voltage across the motor, and current Motora current consumed by the motor, where a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMnoloadMassHammer)×(13 600), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition and mass Hammer a mass of the hammer, and where the fourth power ratio of the rotary impact tool is greater than 65. [66] The rotary impact tool of claim 65, wherein the fourth power ratio of the rotary impact tool is greater than 75. [67] The rotary impact tool of claim 66, wherein the fourth power ratio of the rotary impact tool is greater than 80. [68] The rotary impact tool of claim 67, wherein the fourth power ratio of the rotary impact tool is greater than 85. [69] The rotary impact tool of any of claims 65-68, wherein the bore defines a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, the battery pack having a nominal voltage of at least 18 volts and a nominal capacity of at least 9 Ah, and the rotary impact tool having a total weight including the battery pack of less than or equal to 8.5 lbs. [70] Rotary impact tool, comprising: a housing defining a back of the rotary impact tool and a top of the rotary impact tool; an electric motor carried within the housing; a handle having a first end coupled to the housing and an opposite second end; a battery receptacle coupled to the second end of the handle; a battery pack attachable to the battery receptacle, the battery pack defining a bottom of the rotary impact tool and providing power to the motor when attached to the battery receptacle; and a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, the distal end of the anvil defining a front face of the rotary impact tool, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; where a tool length is defined between the back of the rotary impact tool and the front of the rotary impact tool, wherein a tool height is defined between the bottom of the rotary impact tool and the top of the rotary impact tool, and where a ratio of the tool length to the tool height is less than or equal to 1. [71] A rotary impact tool according to claim 70, wherein the ratio of the tool length to the tool height is about 0.

8. [72] Rotary impact tool according to claim 70, wherein the tool height is less than or equal to 250 mm. [73] Rotary impact tool according to claim 70, wherein the handle has a foot at the second end and the battery holder is coupled to the foot, wherein the rotary impact tool further comprises a trigger on the handle for activating the motor, the trigger having a lower lip in opposing relationship with the base of the handle, wherein a grip height is defined between an upper surface of the foot and the lower lip of the trigger, and where the ratio of the handle height to the tool height is greater than or equal to 0.

3. [74] A rotary impact tool according to claim 73, wherein the handle height is greater than or equal to 87 mm. [75] The rotary impact tool of claim 73, wherein the trigger has a front face and the handle has a back face, and wherein a distance between the front face of the trigger and the back face of the handle is less than or equal to 63 mm. [76] The rotary impact tool of claim 70, wherein the drive assembly is configured to convert continuous torque input from the motor into successive rotary impacts on the workpiece with a fastening torque of at least 900 ft-lbs, wherein the battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah, and wherein the rotary impact tool has a total weight including the battery pack of less than or equal to 7.5 lbs. [77] A rotary impact tool according to claim 76, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [78] The rotary impact tool of claim 76, wherein a ratio of the fastening torque to the total weight is greater than or equal to 120 ft-lbs per pound. [79] The rotary impact tool of claim 76, wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [80] The rotary impact tool of claim 76, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound. [81] A rotary impact tool according to claim 76, wherein a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motora voltage across the motor, and current Motor a current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertia Hammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [82] A rotary impact tool according to claim 81, wherein a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition, and wherein the second power ratio of the rotary impact tool is greater than 2. [83] A rotary impact tool according to claim 82, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [84] A rotary impact tool according to claim 83, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMno loadmasshammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [85] Rotary impact tool, comprising: a housing defining a top surface of the rotary impact tool; an electric motor carried within the housing; a handle having a first end coupled to the housing and an opposite second end, the handle having a foot at the second end; a battery holder coupled to the base of the handle; a battery pack attachable to the battery receptacle, the battery pack defining a bottom of the rotary impact tool and providing power to the motor when attached to the battery receptacle; a trigger on the handle for activating the motor, the trigger having a lower lip in opposing relationship with the base of the handle; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, the distal end of the anvil defining a front face of the rotary impact tool, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; and wherein a grip height is defined between an upper surface of the foot and the lower lip of the trigger, where a tool height is defined between the bottom and the top of the rotary impact tool, and where the ratio of the handle height to the tool height is greater than or equal to 0.

3. [86] A rotary impact tool according to claim 85, wherein the handle height is greater than or equal to 87 mm. [87] Rotary impact tool according to claim 85, wherein the tool height is less than or equal to 250 mm. [88] The rotary impact tool of claim 85, wherein the trigger has a front face and the handle has a back face, and wherein a distance between the front face of the trigger and the back face of the handle is less than or equal to 63 mm. [89] The rotary impact tool of claim 85, wherein the drive assembly is configured to convert continuous torque input from the motor into successive rotary impacts on the workpiece with a fastening torque of at least 900 ft-lbs, wherein the battery pack has a nominal voltage of at least 18 volts and a nominal capacity of at least 5 Ah, and wherein the rotary impact tool has a total weight including the battery pack of less than or equal to 7.5 lbs. [90] A rotary impact tool according to claim 89, wherein the motor is a brushless electric motor including: a stator with a nominal diameter of 60 mm and a plurality of stator windings, and a rotor positioned within the stator and having a plurality of permanent magnets. [91] The rotary impact tool of claim 89, wherein a ratio of the fastening torque to the total weight is greater than or equal to 120 ft-lbs per pound. [92] The rotary impact tool of claim 89, wherein a ratio of a peak output speed of the drive assembly to the total weight is greater than or equal to 280 revolutions per minute and pound. [93] The rotary impact tool of claim 89, wherein a ratio of a peak impact frequency provided by the drive assembly to the total weight is greater than or equal to 350 impacts per minute per pound. [94] A rotary impact tool according to claim 89, wherein a mechanism efficiency of the rotary impact tool is defined as: η∝=BPM×KEHammer,DrillingVoltageMotor×CurrentMotor, where BPM is the number of beats per minute, KE Hammer, Bohren a kinetic energy of the hammer during a state under load and before impact on the anvil, tension Motora voltage across the motor, and current Motor a current consumed by the motor, where a first power ratio (PR1) of the rotary impact tool is defined as: PR1=(η∝InertiaHammer)×(1216 000), where inertia Hammer is a moment of inertia of the hammer, and where the first power ratio of the rotary impact tool is greater than 1. [95] A rotary impact tool according to claim 94, wherein a second power ratio (PR2) of the rotary impact tool is defined as: PR2=(η∝×RPMno loadinertiahammer)×(1216 000 000), where RPM keine Last a rotation frequency of the impact mechanism in a no-load condition, and wherein the second power ratio of the rotary impact tool is greater than 2. [96] A rotary impact tool according to claim 95, wherein a third power ratio (PR3) of the rotary impact tool is defined as: PR3=(η∝MassHammer)×(160), where mass Hammer a mass of the hammer, and where the third power ratio of the rotary impact tool is greater than 2. [97] A rotary impact tool according to claim 96, wherein a fourth power ratio (PR4) of the rotary impact tool is defined as: PR4=(η∝×RPMnoloadMassHammer)×(13 600), and where the fourth power ratio of the rotary impact tool is greater than 65. [98] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil having a bore in a distal end thereof for receiving a tool attachment for performing work on the workpiece, the bore defining a hexagonal cross-sectional shape in a plane oriented transversely to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a spring for biasing the hammer in an axial direction towards the anvil; and a chuck having a body surrounding the anvil, the chuck being movable along the anvil between a first position in which the tool attachment is locked within the anvil and a second position in which the tool attachment is removable from the anvil, wherein the chuck is preloaded towards the first position, and wherein the chuck includes a knurl on an outer surface of the body and a lip extending away from the axis of rotation that is grippable by a user for moving the chuck from the first position to the second position. [99] The rotary impact tool of claim 98, wherein the lip is adjacent to a distal end of the chuck opposite the housing. [100] A rotary impact tool according to claim 99, wherein the lip is annular. [101] Rotary impact tool, comprising: a housing; an electric motor carried in the housing; a drive assembly for converting a continuous torque input from the motor into successive rotational impacts on a workpiece, the drive assembly including: an anvil that has the following: an outer surface, a longitudinal bore in a distal end of the anvil configured to receive a tool attachment for performing work on the workpiece, the tool attachment having an attachment recess, the bore defining a hexagonal cross-sectional shape in a plane oriented transverse to a rotational axis of the anvil, the bore having a nominal diameter of 7 / 16 inch, a piston detent opening extending radially inward from the outer surface to the bore, and a top locking opening extending radially inward from the outer surface to the bore, a hammer for transmitting the successive rotary blows to the anvil, which is movable both rotationally and axially with respect to the anvil, and a hammer spring for biasing the hammer in an axial direction towards the anvil; a top detent disposed in the top detent opening, the top detent being movable between a first top detent position in which the top detent is at least partially located in the bore and a second top detent position in which the top detent is located outside the bore; a piston in the bore, the piston having a piston detent recess; a piston detent disposed in the piston detent opening, the piston detent being movable between a first piston detent position in which the piston detent is at least partially located in the piston detent recess and a second piston detent position in which the piston detent is located outside the piston detent recess; a piston spring that biases the piston toward the distal end of the anvil; an O-ring disposed at least partially within the attachment locking opening; and a chuck surrounding the anvil, the chuck being movable along the anvil between a first chuck position in which the piston detent is prevented by the chuck from moving from the first piston detent position to the second piston detent position, and the attachment detent is prevented by the chuck from moving from the first attachment detent position to the second attachment detent position, and a second chuck position in which the piston detent is movable by the piston from the first piston detent position to the second piston detent position, and the attachment detent is movable from the first attachment detent position to the second attachment detent position, wherein the chuck is preloaded towards the first chuck position, wherein, when the chuck is in the second chuck position and the tool attachment is inserted into the bore, the O-ring is deformable by the attachment detent so that the attachment detent is movable by the attachment from the first attachment detent position to the second attachment detent position, wherein, when the chuck is in the first chuck position and the tool attachment is in the bore, the attachment detent is in the attachment recess so that the tool attachment is locked within the bore, and wherein, when the chuck is moved from the first chuck position to the second chuck position while the tool attachment is in the bore, the tool attachment is ejectable from the bore by the piston. [102] The rotary impact tool of claim 101, wherein the chuck has a first inner piston detent surface and a second inner piston detent surface having a larger diameter than the first inner piston detent surface, and wherein, when the chuck is in the first chuck position, the first inner piston detent surface prevents the piston detent from moving to the second piston detent position, and wherein, when the chuck is in the second chuck position and the piston detent moves to the second piston detent position, the piston detent is in contact with the second inner piston detent surface. [103] The rotary impact tool of claim 101, wherein the chuck has a first inner attachment detent surface and a second inner attachment detent surface having a larger diameter than the first inner attachment detent surface, and wherein, when the chuck is in the first chuck position, the first inner attachment detent surface prevents the attachment detent from moving to the second attachment detent position, and wherein, when the chuck is in the second chuck position and the attachment detent moves to the second attachment detent position, the attachment detent is in contact with the second inner attachment detent surface. [104] The rotary impact tool of claim 101, wherein when the chuck is moved from the first chuck position to the second chuck position, the movement of the attachment detent from the first attachment detent position to the second attachment detent position is inhibited by the O-ring. [105] The rotary impact tool of claim 101, wherein the piston includes an intermediate flat having a larger diameter than a diameter of the piston detent recess, and wherein, when the chuck is in the second chuck position, the piston detent is held against the intermediate flat. [106] The rotary impact tool of claim 101, further comprising a washer on the anvil and a chuck spring abutting against the washer such that the chuck spring biases the chuck toward the first chuck position. [107] A rotary impact tool according to claim 106, wherein the O-ring abuts the washer. [108] The rotary impact tool of claim 106, further comprising a clamp that limits the extent to which the chuck spring biases the chuck such that the chuck abuts the clamp in the first chuck position. [109] A rotary impact tool according to claim 108, wherein the clamp is arranged in a circumferential groove of the outer surface of the anvil. [110] The rotary impact tool of claim 101, further comprising a rib on an outer surface of the chuck. [111] The rotary impact tool of claim 101, further comprising a bearing disposed on the outer surface of the anvil, the bearing rotatably supporting the anvil with respect to the housing. [112] A rotary impact tool according to claim 111, wherein the bearing is pressed into the anvil. [113] A rotary impact tool according to claim 101, further comprising a circumferential O-ring groove in the anvil and in which the O-ring is held. [114] The rotary impact tool of claim 113, wherein the attachment locking opening intersects the O-ring groove.

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